Audiolab DC Block
- Thread starter ff1d1l
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Mynamemynaim
38yrs a Naim owner
A DC blocker is effective at stopping mains born DC
It makes the transformer quieter ...IF it's affected by DC
Not sure it actually improves the sound quality out of the speakers though ?
(Yes...I have used DC blockers and isolation transformers before)
It makes the transformer quieter ...IF it's affected by DC
Not sure it actually improves the sound quality out of the speakers though ?
(Yes...I have used DC blockers and isolation transformers before)
uncl_nigel
pfm Member
My experience of the Isotek Syncro DC Blocker would suggest that some of the claims in the video are a little optimistic.
DC Blockers tend to address buzzing transformers rather than the sound coming out of the speakers.
That being said the price quoted is definitely more affordable than the 1st generation Syncro I use.
I have used balanced isolation transformers but they have a tendency to buzz :-(
EDIT given post#3 below: I use mine on the SME turntable power supply. Both SME 20 mk2 and mk3 power supplies buzz without the DC blocker. My dCS and Aesthetix boxes don't need the Syncro - probably include appropriate internal counter-measures. My previous Naim stuff did need DC blocking.
DC Blockers tend to address buzzing transformers rather than the sound coming out of the speakers.
That being said the price quoted is definitely more affordable than the 1st generation Syncro I use.
I have used balanced isolation transformers but they have a tendency to buzz :-(
EDIT given post#3 below: I use mine on the SME turntable power supply. Both SME 20 mk2 and mk3 power supplies buzz without the DC blocker. My dCS and Aesthetix boxes don't need the Syncro - probably include appropriate internal counter-measures. My previous Naim stuff did need DC blocking.
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earlofsodbury
Wastrel.
While there's no definitive answer possible to this question because every case will be different, a transformer that is buzzing due to AC waveform clipping ('DC offset') is undergoing severe saturation causing audible magnetostriction - the loss of efficiency is significant while this is happening, something like 90% loss is common. IME, that will be most obvious in bass performance.
The flipside is an underspecified DC blocker - in the case of designs featuring capacitors at least - will negatively impact power stage dynamics, so cheap/bodge solutions are very-much to be avoided.
I believe designs like the ifi one use a solid state solution, but I'm not up to date with how they go about it. It's proven difficult to make cap-based solutions CE-compliant because they rely on high ripple-current / lowish voltage non-mains class caps so as not to restrict current. They're perfectly safe, but apparently 'computer says "no"'...
cctaylor
pfm Member
I have the ATL DC Blocker V3. While it hasn't stopped all the mechanical hum it has eliminated the annoying higher level intermittent hum which plagued my system. It can supplied with a range of connections to suit your needs. Standard fuse is 8amp with 10amp optional. The unit is CE marked.
Can't say I noticed any change in sound quality.
The Audio lab is limited to 600va, I don't think it would suit my system with 3 X NAP250s.
Can't say I noticed any change in sound quality.
The Audio lab is limited to 600va, I don't think it would suit my system with 3 X NAP250s.
cctaylor
pfm Member
Some transformers just hum, others hum worse when there is a DC offset on the mains. Whether DC Blocker makes a difference all depends on why your transformer hums.
Our houses and our neighbours houses are full of smps of varying design quality these days. We had to replace the single RCD on one half of the consumer board with individual MCBOs to avoid nuisance trips. The electrician believes that the little bits of offset from lots of smps adds up and upsets the RCD.
davidsrsb
pfm Member
There used to be equipment that drew power unequally from positive and negative cycles eg live chassis TVs and thyristor power controls. These have largely vanished due to regulations on mains current harmonics.
Also, earth might not be 0V if you live near a 3rd rail electric railway
Also, earth might not be 0V if you live near a 3rd rail electric railway
DuncanF
pfm Member
TIL! But even is earth is not at 0V, if Neutral is bonded to it they must be equipotential.
John Phillips
pfm Member
See the half-wave rectified appliance example under "How DC Appears on the Mains" on the Rod Elliott audio page here.
The key phrase is "by half-wave rectifying the mains in this manner, there is an inevitable interaction with the mains impedance". This interaction occurs only on one mains polarity and hence causes a DC offset.
It could get very expensive if you entertain thoughts like that. And lots of boxes on the floor
hifinutt
hifinutt
i am just playing with my isotek syncro on a modest cd player . compared to another brand of mains filter
it was pretty effective on an arcam integrated , tightened everything up . i had no problems with dc but I do find it can improve sound sometimes . the most effective was a puresound L10 pre amp which really made a difference
at some point i may sell the syncro to raise funds though
Arkless Electronics
Trade: Amp design and repairs.
It will be just as effective in removing the buzzing sound from any mains transformer (ie a mechanical buzzing from the item itself, not buzzing through the speakers) which is generating the buzz due to DC on the mains specifically.
Some transformers will buzz anyway....
It won't effect sound quality.
uncl_nigel
pfm Member
Same opinion here. Never noticed any significant sound improvement with the Isotek Syncro but it is effective on transformer buzz caused by DC - that's why I keep it but only use it on one item, an SME 20 power supply.
martin clark
pinko bodger
You have it right: this is not actually any significant DC-voltage offset - there really is not any - but what effects arise from, and appear the same as 'dc offset' to cursory measurement technique because it is hard to tell apart without some refinement and no little effort - is significant 2nd harmonic distortion.
See the posts by @davidsrsb and @John Phillips above. HTH.
earlofsodbury
Wastrel.
I've got a caps-and-diodes based blocker here, using 33,000uF 15VDC electrolytics that has been in constant use since 2007. TBH, if any of the components ever see high enough current or voltage to break them, you'll probably also have smouldering wires hanging out of your plasterwork...